+/* reliable-chat - multipath chat
+ * Copyright (C) 2012 Scott Worley <sworley@chkno.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
package main
import "container/list"
import "encoding/json"
+import "expvar"
+import "flag"
import "log"
import "net/http"
+import "strconv"
import "time"
+var port = flag.Int("port", 21059, "Port to listen on")
+var localaddress = flag.String("localaddress", "", "Local address to bind to")
+var max_messages = flag.Int("maxmessages", 1000, "Maximum number of messages to retain")
+
+var start_time = expvar.NewInt("start_time")
+var speak_count = expvar.NewInt("speak_count")
+var fetch_count = expvar.NewInt("fetch_count")
+var fetch_wait_count = expvar.NewInt("fetch_wait_count")
+var fetch_wake_count = expvar.NewInt("fetch_wake_count")
+var drop_due_to_limit_count = expvar.NewInt("drop_due_to_limit_count")
+
type Message struct {
Time time.Time
+ ID string
Text string
}
}
type Store struct {
- Add chan Message
- Get chan StoreRequest
+ Add chan *Message
+ Get chan *StoreRequest
}
-// TODO: Monotonic clock
+var monotonic_clock chan chan time.Time
+
+const minimum_clock_increment = time.Millisecond
+
+func start_clock() {
+ internal_monotonic_clock := make(chan chan time.Time, 1)
+ go func() {
+ last_time := time.Now()
+ main:
+ for {
+ select {
+ case request, ok := <-internal_monotonic_clock:
+ if !ok {
+ break main
+ }
+ earliest_acceptable_time := last_time.Add(minimum_clock_increment)
+ current_time := time.Now()
+ if current_time.Before(earliest_acceptable_time) {
+ current_time = earliest_acceptable_time
+ }
+ request <- current_time
+ last_time = current_time
+ }
+ }
+ }()
+ monotonic_clock = internal_monotonic_clock
+}
+
+func now() time.Time {
+ c := make(chan time.Time, 0)
+ monotonic_clock <- c
+ return <-c
+}
func manage_store(store Store) {
messages := list.New()
message_count := 0
- max_messages := 1000
waiting := list.New()
+main:
for {
select {
- case new_message := <-store.Add:
- messages.PushBack(new_message)
+ case new_message, ok := <-store.Add:
+ if !ok {
+ break main
+ }
+ speak_count.Add(1)
for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
- waiter.Value.(StoreRequest).Messages <- []Message{new_message}
- close(waiter.Value.(StoreRequest).Messages)
+ waiter.Value.(*StoreRequest).Messages <- []Message{*new_message}
+ close(waiter.Value.(*StoreRequest).Messages)
+ fetch_wake_count.Add(1)
}
waiting.Init()
- if message_count < max_messages {
+ messages.PushBack(new_message)
+ if message_count < *max_messages {
message_count++
} else {
messages.Remove(messages.Front())
+ drop_due_to_limit_count.Add(1)
}
- case request := <-store.Get:
- if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(Message).Time) {
+ case request, ok := <-store.Get:
+ if !ok {
+ break main
+ }
+ fetch_count.Add(1)
+ if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) {
waiting.PushBack(request)
+ fetch_wait_count.Add(1)
} else {
start := messages.Back()
response_size := 1
- if messages.Front().Value.(Message).Time.After(request.StartTime) {
+ if messages.Front().Value.(*Message).Time.After(request.StartTime) {
start = messages.Front()
response_size = message_count
} else {
- for start.Prev().Value.(Message).Time.After(request.StartTime) {
+ for start.Prev().Value.(*Message).Time.After(request.StartTime) {
start = start.Prev()
response_size++
}
}
response_messages := make([]Message, 0, response_size)
for m := start; m != nil; m = m.Next() {
- response_messages = append(response_messages, m.Value.(Message))
+ response_messages = append(response_messages, *m.Value.(*Message))
}
request.Messages <- response_messages
}
}
func start_store() Store {
- store := Store{make(chan Message, 20), make(chan StoreRequest, 20)}
+ store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)}
go manage_store(store)
return store
}
+const robots_txt = `User-agent: *
+Disallow: /
+`
+
func start_server(store Store) {
http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
var since time.Time
}
}
messages_from_store := make(chan []Message, 1)
- store.Get <- StoreRequest{since, messages_from_store}
+ store.Get <- &StoreRequest{since, messages_from_store}
json_encoded, err := json.Marshal(<-messages_from_store)
if err != nil {
return
}
w.Header().Add("Content-Type", "application/json")
+ w.Header().Add("Access-Control-Allow-Origin", "*")
w.Write(json_encoded)
})
http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
- store.Add <- Message{time.Now(), r.FormValue("text")}
+ store.Add <- &Message{
+ now(),
+ r.FormValue("id"),
+ r.FormValue("text")}
+ w.Header().Add("Access-Control-Allow-Origin", "*")
+ })
+
+ http.HandleFunc("/robots.txt", func(w http.ResponseWriter, r *http.Request) {
+ w.Write([]byte(robots_txt))
})
- log.Fatal(http.ListenAndServe(":8080", nil))
+ log.Fatal(http.ListenAndServe(*localaddress+":"+strconv.Itoa(*port), nil))
}
func main() {
+ flag.Parse()
+ start_clock()
+ start_time.Set(now().UnixNano())
store := start_store()
start_server(store)
}
projects / reliable-chat / blobdiff